Connection indicator for connector having a resistive pin



W. F. CARR Dec 3, 1968 CONNECTION INDICATOR FOR CONNECTOR HAVING A RESISTIVE PIN Filed April 3, 1967 W/. BY

INVENTOR; Jami 6422 A nuns United States Patent 3,414,806 CONNECTION INDICATOR FOR CONNECTOR HAVING A RESISTIVE PIN William F. Carr, Santa Monica, Calif., assignor, by mesne assignments, to McDonnell Douglas Corporation, Santa Monica, Calif., a corporation of Maryland Continuation-impart of application Ser. No. 313,064, Oct. 1, 1963. This application Apr. 3, 1967, Ser. No. 627,890

6 Claims. (Cl. 324-65) ABSTRACT OF THE DISCLOSURE An indicator for determining whether or not the halves of a two-piece electrical connector are properly connected together. A resistive pin in a plug engages the receptacle of a socket and presents no more resistance across the connection when properly connected than the resistance in other pin and receptacle connections. However, when the connection is not properly connected, a portion of the resistance on the pin is in the circuit in which ohmic readings are taken and presents a higher resistance to the circuit, which indicates that the connection is not properly made.

RELATED APPLICATIONS This is a continuation-in-part of copending patent application Ser. No. 313,064 for Electrical Connector Indicator, filed Oct. 1, 1963, by William F. Carr, now abandoned.

BACKGROUND OF THE INVENTION Many types of electrical connectors are known for connecting one electrical component to another. These connectors usually employ pins or the like on one component which engage receptacles on another component. When such connectors are located in remote or inaccessible places where they cannot be visually observed, it is practically impossible to determine at any particular time whether or not the connector halves are properly and fully engaged or connected together.

SUMMARY OF THE INVENTION An electrical connector is provided having means for remotely indicating the percentage of physical engagement of the pins of one connector half with the associated receptacles of the olher connector half. This is done by coating one of the pins with a resistive material of known value which adds resistance to the resistive circuit in which the connector is employed when the connection is improperly made. However, this resistive pin does not present a substantially higher ohmic resistance to the circuit when there has been a proper connection.

In a first embodiment, a printed circuit board is proi vided with a special pin or wiper having a coating of a resistive material of a known value, such as sprayed carbon. The length of this coating is the same as the depth of engagement of the wiper in a receptacle. The wiper is connected in a circuit in such a manner that the percentage of engagement of the wiper with its associated receptacle is reflected in a predetermined change in the ohmic resistance of the circuit.

According to a second embodiment, two spaced pins of the printed circuit board are coated with the resistive material and are connected in series in a circuit in such a manner that changes in the ohmic resistance of the circuit will also indicate whether or not the printed circuit board is angularly displaced with respect to its socket.

According to a third embodiment, a cylindrical connector having a plurality of pins and receptacles in each half is provided with one or more pins made of a material, such as Nichrome, having a predetermined resistive value so that the resistance across the connector leads will have a predetermined value only when the pins fully engage their respective receptacles.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings, in which which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial elevational view, with parts broken away to show internal construction, of an electrical connector constituting a first embodiment of the present invention;

FIG. 2 is a schematic, wiring diagram of the device of FIG. 1;

FIG. 3 is an enlarged, cross-sectional view of one of the pins of FIG. 1 shown in engagement with its associated receptacle;

FIG. 4 is a schematic wiring diagram of a second embodiment of the present invention; and

FIG. 5 is an elevational view, with parts broken away to show internal construction, of a third embodiment of the present invention.

Referring again to the drawings and more particularly to FIGS. 1-3, an electrical connector 10 constituting a first embodiment of the present invention includes a printed circuit board 12 having a plug strip 14 engageable with a socket 16.

The printed circuit board 12 has conventional electrical circuit leads 18, 20, 22, 24, 26 and 28 thereon Which, for convenience, terminate in connecting pads 30, 32, 34, 36, 38 and 40. It is to be understood, of course, that circuit boards have innerconnections between certain of the leads and also have selected electrical components mounted thereon, and that this illustration is for purposes of convenience, only. The leads terminate as pins or wipers 42, 44, 46, 48, 50 and 52 on the plug strip 14. These pins mate with and are insertable into receptacles 54, 56, 58, 60, 62 and 64 on the socket 16. These receptacles, in turn, have leads 66, 68, 70, 72, 74 and 76 to which external electrical leads may be fastened for the energization of the circuits and components on the printed circuit board 12. Socket 16 typically is fastened to a chassis and is adapted to receive selected circuit boards for use.

The foregoing description is illustrative of a typical conventional circuit board which may he modified in accordance with the present invention. This involves the coating of one of the leads 46 with a suitable high-resistance material, such as sprayed carbon 78. This coating has a known value of resistance which varies linearly and extends over the pin 46 a distance equivalent to the depth of the associated receptacle 58.

A suitable connection such as lead 80 innerconnects this pin 46 with one of the other pins, such as pin 42. This connection 80 represents a resistive circuit which finds use in the functioning of this particular circuit board 12, or in the alternative, may represent a special interconnection for the purpose ofthis invention. It may be made in the same manner as the other leads or it may be a special shorting element which makes this innerconnection. Similarly, connection 82 completes the circuit between pin 44 and pin 42. Pin 44 does not have this high-resistance material.

When it is desired to determine whether or not the printed circuit board 12 is fully engageable with socket 16, as shown in FIG. 3, a meter 84, shown in FIG. 2, is

placed across contacts 66, 68 which have a resistive circuit therebetween represented by connection 82 in FIG. 2. The ohmic resistance of this circuit is then noted. Thereafter, contact 86 is removed from lead 68 and placed in contact with lead 70 to place the resistive pin 46 in the circuit, as indicated by the wiper arm (receptacle 58) on resistance 78, the degree of resistance of which depends upon the completeness of the connection. If the connection is properly made, the resistance reading by ohmmeter 84 when contact 70 is in the meter circuit, will be the same as that previously read. For best results, it is preferable that the resistive connection be placed in the center of the plug strip 14 of the circuit board 12 and that the circuit having the lower resistance include adjacent contacts, such as 66, 68, shown in FIG. 2. When the connection is not properly made, the resistance reading by meter 84 will be increased by an amount inversely proportional to the percentage of physical engagement of the pin 46 with receptacle 58.

It is possible for the pin 46 to be in complete engagement with receptacle 58 and another pin, such as the pin 52, to be in partial engagement with its receptacle because of angular displacement of plug strip 14 with respect to socket 16. Consequently, in the second embodiment of the present invention, two spaced pins on the printed circuit board are coated with the resistive material and are connected together in series in the printed circuit in such a manner that changes in the ohmic resistance of the circuit will indicate whether or not the plug strip 15 is angularly displaced with respect to socket 16. This embodiment is shown in FIG. 4 wherein an electrical connector 10a has the same general construction as the connector 10 in FIG. 1. However, pins 44 and 50, which are spaced apart on the circuit board, have resistive coatings 78 thereon and are connected in series by a connection 80a. Connection 81a completes the circuit between contacts 66 and 76. Meter 84 is shown connected to the contacts 66 and 76 so that the ohmic resistance can be measured in a circuit not having the resistive pins therein. Thereafter, meter 84 is connected to contacts 68 and 74 having both resistive pins 44 and 50 therein. At this time, the meter 84 will have a higher ohmic reading than before when either of the pins 44 or 50 are only partially seated in their respective receptacles. Since the pins are spaced apart on the circuit board, and if both are properly connected such that the ohmic resistance reading is the same as before, then assurance is given that all pins on the circuit board are in proper contact.

Referring now to FIG. 5, a third embodiment of the present invention comprises a cylindrical electrical connector, generally designated 86. The connector 86 includes an upper connector portion 88 and a lower connector portion 90.

A plurarity of pins 92 are mounted in the upper portion 88 and depend from the lower face 94 thereof. The outer pins 92a and 92b are made from a material, such as Nichrome, having a high electrical resistance which varies linearly over the length of the pins. The remaining pins may be conventional electrical connector pins of low resistance. An electrical lead 96 is connected to each pin 70 for connecting the upper portion 88 in an electrical circuit, not shown. A plurality of receptacles 98 are mounted in the lower portion 90 and are engageable by the pins 92. An electrical lead 100 is connected to each receptacle 98 so that the lower portion 90 may also be connected in an electrical circuit, not shown.

When the pins 92a and 92b are engaging their receptacles 98 to the depth shown in FIG. 5, a meter 84a placed across the associated leads 96 and 100 indicates an ohmic resistance which is inversel proportional to the depth of engagement of an associated pin 92a or 92b. Thus, should either one or both the pins 92a and 92b be not in full engagement with its associated receptacle 98, the meter 84a, when placed across the associated leads 96 and 100, will indicate an ohmic resistance which is more than that for full engagement of the pins. This reading can be taken before installation or with low resistance pins 92 in the circuit and used as a basis for comparison.

While the particular electrical connectors herein shown and described in detail are fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that they are merely illustrative of the presently preferred embodiments of the invention. For example, certain of the receptacles may be made resistive instead of their associated pins. Any connection that is made to have a resistance in a difierent amount when improper connection is made than when proper connection is made. Accordingly, no limitations are intended in the details of construction or design of embodiments of this invention other than as defined in the appended claims.

I claim:

1. Indicator means for indicating the engagement of pin means with receptacle means in an electric circuit connector comprising:

an electrical connector including a plug portion haviing pins extending therefrom and a socket portion with receptacles therein to receive the said pins,

at least one of said pins having resistive means formed on its mating end indicative of engagement between the pin and receptacle,

circuit means interconnecting at least three of said pins at their respective non-mating ends including the pin having the resistive means, and

meter means for connection across respective pairs of non-mating ends of the receptacles associated with the pins having said circuit means for comparing the resistance across said one pin and receptacle with the resistance across the other of said pins and receptacles.

2. An indicator means as in claim 1 wherein said resistive means comprises an electrically resistive material coated on said pin.

3. An electrical connector indicator means as in claim 1, said meter means being sequentially connectable across said one pin and receptacle and thereafter connectable across another of said pin and receptacles.

4. An electrical connector indicator means as in claim 1 wherein said resistive means presents a resistance inversely proportional to the percentage engagement of said one pin in its associated receptacle.

5. An electrical connector indicator means as in claim 1 wherein said meter means comprises an ohmmeter.

6. An electrical connector indicator means as in claim 1 and a second pin having resistive means formed on its mating end indicative of engagement between the pin and receptacle, said second pin spaced from the first said pin and receptacle.

References Cited UNITED STATES PATENTS 1,998,525 4/1935 Russell 338-219 2,666,898 1/1954 Meldal 324-66 2,896,186 7/ 1959 Hardmark 339- 2,964,701 12/1960 Argabright 324-66 XR 3,265,968 8/1966 Bilodeau et al 324-66 FOREIGN PATENTS 141,036 6/ 1953 Sweden.

RUDOLPH V. ROLINEC, Primary Examiner. E. E. KUBASIEWICZ, Assistant Examiner. 

